1. Field of the Invention
The present invention relates to a method of making a vacuum vessel. In particular, the present invention relates to a method of making a flat image forming apparatus.
2. Description of the Related Art
Examples of existing flat image forming apparatuses include field emission displays (FEDs) and surface-conduction electron-emitter displays (SEDs). A vacuum vessel used for an image forming apparatus is generally made by disposing a face plate and a rear plate with a predetermined distance therebetween, then melting a sealing member disposed between the plates so as to bond and seal the vacuum vessel. In order to provide a secure seal, the plates are pressed against each other with a force perpendicular to the plates.
Japanese Patent Laid-Open No. 2006-93117 (corresponding U.S. Patent Application Publication No. 2006/0042316 A1) describes a method of securing conductance during a baking step and adjusting the positions of plates in in-plane directions thereof. To be specific, the relative positions of the face plate and the rear plate are fixed, the plates are fastened to each other using a positioning jig capable of adjusting the distance between the plates, and the distance between the plates is controlled using an arm that raises one of the plates.
However, it is difficult to control a pressure applied to a plate to be strictly perpendicular to the plate. Thus, when a pressure is applied to a surface of the plate, a force is generated in an in-plane direction of the plate, which is a direction parallel to the principal surface of the plate. This force may cause the relative positions of the face plate and the rear plate to deviate. Moreover, because the baking process is performed in a reduced-pressure atmosphere, it may be necessary to bond and seal the plates in the same reduced-pressure atmosphere after the baking process has finished. Therefore, it is difficult to use a large apparatus to bond and seal the plates.